


Last promise

by shadowarchives



Series: The Undertale Trilogy (Untold Episodes) [1]
Category: Undertale (Video Game)
Language: English
Status: Completed
Published: 2017-02-01
Updated: 2017-02-03
Packaged: 2018-09-21 10:43:25
Rating: Not Rated
Warnings: No Archive Warnings Apply
Chapters: 4
Words: 2,786
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/9544694
Author URL: https://archiveofourown.org/users/shadowarchives/pseuds/shadowarchives
Summary: Everything seems to be fine now that Monsters are finally on the surface.But what about Frisk, Is Chara's corrupted Determination giving her side effects.Can Asriel somehow change from his normal form to a flower at will.And how is Sans reacting to their situations after all their hard work.





	1. Good hope

"Hey papyrus, is she alright." Papyrus closes the door looking sad "I don't know, that Corrupted determination thing must've really been bad." Sans and Papyrus were talking quietly outside Frisks room. She had felt unwell the past few days, Gaster suggested to Toriel that she should stay with the Skeleton brothers while she helps out in the school during the weekend and while he goes to help in developments to sustain Humans and Monsters in the future. Since then the brothers have been trying everything they could to keep her alright. Luckily Sans being the problem solver he was might have a solution he hasn't told Papyrus about yet. "I need to see them Pap." Papyrus looked worried but then agreed with is brother as he went downstairs. It was almost dinner and he had to sort the food out for the others.

Sans slowly opened the room to see Frisk looking terrible, She could barely move, her face was red yet she was slowly shivering. "Hey kid." She stuttered over her words for a moment "S-s-sans? Wh-where are y-you?" She stopped shivering violently when his bony hand held hers calming her down "I'm here kid. I've got something that might help you. Now i need you to trust me in case you do feel a little twitch, but i promise this won't hurt a bit ok?" Frisk nodded slowly as Sans pulled her Soul out and poured a blue liquid onto it, saving half of it and stashing it back in his pocket as he sat down on the bed Frisk was lying on. The kid felt a little pain and an audible noise of stress was heard, Sans felt slightly guilty knowing what the Liquid used to do to him. he lied down and pulled an arm over her shoulder as the liquid took effect "Thank you Sans." Frisk said as she started the become calmer "It's ok kid, i'll let you get some rest, Papyrus is almost done with dinner so if you don't want to miss his spaghetti then i suggest you make your way down soon, he wouldn't you to forget-ti his spaghetti, heheheh." Frisk chuckled a little sitting up after hearing that joke. Sans felt he had done his job then left the room and walked downstairs to the kitchen. He pulled out the liquid he used earlier. "Well i guess i should use the rest of it."

Papyrus turned round to see Sans swallowing the rest of the liquid and storing the test tube in a cabinet along with three others. "What is that." Sans turned round whilst shutting the cabinet "It's something Gaster developed that you never heard about, I won't go into detail about it, but it's called Serifim." Papyrus the saw Sans grabbed his phone and heading to the front door. "Where do you think you're going." Sans looked back smiling "Just going for a walk y'know, a lazy bones like me could do with it. After all it's a nice day out." Sans looked concerned saying that last line, but shrugged it off as he waved to Papyrus as he shut the door. Papyrus waved back wondering what had gotten into him

**Notes for the Chapter:**

> Hope you guys enjoy the first untold episodes, The liquid mentioned called Serifim is based on one of Sans' fonts  
> (Comic sans and Sans Serif) how it works will be properly explained in one of the other Untold chapters. But you'll have to wait for its release. until then though i hope you enjoyed this episode


	2. Bad day

Sans walked around for a while before nearing some of the lakes below Mt Ebott. "Man, it's good to be alive for once, i never thought i would get to the surface again." He says sitting down. He suddenly notices something glowing in the lake. "... What the hell is that." Suddenly a familiar voice is heard to the right of him "a SAVE point."

He turns round to see a ghostly figure of Chara standing to his right. she looked less of the demon spawn of a monster she was before. But he couldn't help igniting his left eye in case of trouble "What are you doing here. Trying to kill me on my own." Chara chuckled quietly "Actually quite the opposite. I thought i'd return to the lake for a while." She says, Sans eye dims back to his two white pupils as Chara sits down next to him "Really, i hope this isn't a trick. Otherwise you're gonna have a bad time." 

Chara turns round sadly smiling "I can't trick you anymore. Even if i wanted to i physically can't because of the lack of determination." Sans still looks confused and remembers the state Frisk was in during the afternoon "Oh yeah, should probably say Frisk isn't feeling that well because of what you did to her soul." Chara looks a little guilty showing Sans that this wasn't who fought them a long time ago "I'm sorry for that, i didn't realize the side effects of what would happen. If i could do something i would but, i don't see the point. It seems like you have everything in control." 

Sans forgets what he remembered of Chara and the two of them stare down at the lake, Sans however continues to talk "Hey, let me ask you something. If you believe there is some special power that you have, isn't it your responsibility to do the right thing." Chara turns round with a small smile "Yes, but i can't do anything, there is something down in the lake that is keeping me tied here, if i try to go further away from here i materialize and return back in the lake." Sans looks confused, what could possibly be down there keeping this spirit here. "You want to have a look." Is all that he hears before an invisible forces throws him into the lake and everything becomes quieter, The water was perfectly clear, unusual for a body of water so close to the mountain, he realizes what was down there. The broken fragments of his Save star that saved his life long ago, but was no longer needed. He eventually teleports back on the surface. 

Spluttering water and gasping for air he looks up at Chara with a "What the hell was that for." Chara only chuckled "Sorry, got a bit carried away with my monologue of sorts." Sans moved back to where he was and sat back down still drying himself out "Why is that connected to you." "Simple isn't it. It contains determination, if there was one way to look on from what happened i wanted it to be under the shade of the mountain... You see we never figured it out but, my soul and Frisks. are completely different souls of determination." Sans looked confused "How?" "Well i mentioned that the colour black represents hate, But Frisks soul is normally pure red, and a red soul can only be pure red if no violent actions have occurred." Sans understood now "So her soul isn't just a determined soul, Red doesn't mean Determination. It means mercy!" Chara nodded "That's right. But both souls can be classed as the same type as both actions require the same drive to commit to." 

Sans thought over it before he completely understood and decided it was time to go back to his house "Well i better be off... Should i tell Frisk you were here." Chara shook her head "I think it would just make her upset, but let her know that if she does see me again, think only of me as i am now. And she should know that any repercussions of the past events are not by me. But by the hatred that was once present..." Sans thought for a moment but nodded in agreement and waved as he left "alright then, be seeing ya." Chara smiled and looked down at the locket around her neck "Goodbye."

**Notes for the Chapter:**

> The sub plot made here is not canon to Toby fox's version of Undertale, but is a representation of why Chara's soul is different to Frisks, despite them technically being the same type, their actions differentiate what they are.  
> Two more chapters to go...


	3. Bad Dream

Sans watched as a figure of himself had utter terror in his eyes "FRISK!... R-RUN FRISK!!" His ghostly image says before crumbling strangely quick into dust. He then turns round to see the face of a more evil Chara than what he had seen before, as Frisk was injured and her soul was taken from her. a red light clouded the sky and Sans shut his eyes. "This can't be happening!" He says as the red light engulfs him and his body is ripped apart...

He woke up screaming murder, Luckily it was quiet enough so no one heard him. He shook his head "it's just a dream, just a nightmare. Damn it Sans i know you're an Insomniac but this is just ridiculous... Guess i need some fresh air." Sans says to himself and he teleports outside the front door into the garden, looking out to the stars "Man, hey kiddo, if you're listening then i want you to know i wouldn't be here if it wasn't for you. I'm so happy to see these stars again." Sans stayed there for a while before turning round to head back indoors, however a voice came from behind "Howdy partner." It was Asriel, but he looked like Flowey again.

"Hey Asriel, rough night?" Flowey looked down scowling "Tell me about it, lost all my soul energy again trying to keep fights at bay during school so i've reverted back to this. Thank god Gaster developed serifim to speed up the process of changed back to my old self huh." Sans chuckled "Yeah, otherwise you'd have a bone to pick with em huh." Flowey chuckled slightly "Some things never change for you." Looking at the tube of serifim Sans held in his hand, Sans pours a little on him "Mind the petals trashbag!" He says whilst he absorbs the majority of the liquid "Sorry buddy, anyways it should take effect sooner or later." Flowey nods "Which reminds me, why are you up so late." Sans sighed "Nightmare again, living through the incident at judgement hall and if it went all wrong still haunts me to this day... There's something i should probably tell you by the way. I saw her today. We didn't fight, we just talked." Flowey looked shocked but Sans knew it hurt his heart to hear this.

"She's still around. I hope she's alright. What did she say." Flowey says whilst Sans rubs a tear away that was building up in his eye "She's fine, she wanted to let you know she'll be alright and that if you see her, remember her as she is now. No longer filled with hate." 

Sans and Flowey sat there for a while until Flowey broke the silence "Hey Sans. Do i still have your word about that promise we made, that you and I can't tell Frisk about this transformation until she's ready." Sans nodded "Yeah sure. After all it's about time we put our differences aside instead of fighting each other all the time." Flowey looked disgusted "I still hate you, you know." He says rolling his eyes in sarcasm. "Heheheh just messing with ya." Sans says chuckling , Flowey couldn't help but chuckle too.

"Well i better be off, Mom is probably worried sick about me. I'll see you around Sans." Sans nodded "See you around Asriel." Flowey digs back into the dirt whilst Sans teleports back to his room.


	4. Goodnight

"Welp i better get some sleep too, hopefully nothing else happens or-" Suddenly he hears footsteps "Damn it. I must've woken Papyrus." The door opens but Sans doesn't see who it is "Hey Papyrus i'm alright ok, you can go back to sleep." A stressed yet simple response of "No" comes from the door and Sans rubs his eyes trying to see better "Honestly i'm fine. Just go back t-" But Sans then realized who it was and his pupils shrunk in slight guilt "I had a nightmare too. And i wanted to check you're ok." It was Frisk. "Hey kid, i'm sorry to wake ya, i just got a little startled tonight that's all... you ok?" Frisk shook her head with a sad look on her face "Sans, was your nightmare about that fight we had... It's just, i can't make it stop. I wish i could but i, just... I just." Frisk was shivering and looked like tears were building up. 

"Hey kid it's ok, I didn't mean to worry you. It's alright. Come here, you can sit with me if you want." Frisk obliged climbing onto the bed where Sans was sitting on. He put an arm on her shoulder while pulling the sheets over the two of them. "What happened? You wanted to talk about it right?" Frisk nodded grabbing one of Sans' hands which Sans clung onto reassuringly "Every time i dream, I dream of Chara, It must be related to the effects she caused before on my soul. Terrible thoughts of her erasing the world. And me dying." Sans eyes widened "That's weird. Cause, i seem to be having that same dream too." Frisk looks up at him with worry "I don't want any of that to happen, you're all like family to me and. I just don't want you all to leave me again. I never asked for any of this to happen, and i'm genuinely sorry for everything. Please forgive me Sans." Sans pulled Frisk closer and wrapped his arms round their shoulder, Frisk cried silently into his jacket and his shirt was damp eventually with tears while she returned the hug fiercely. Sans brought another arm to her head holding her close and carefully digging through her hair comfortingly.

"It's alright Frisk, i'm here, We all are, I may still be a wisecracking joker but i'm still here. There's nothing to worry about." Sans says quietly "Don't leave me Sans. Please don't leave." Frisk says, with evident grief in her voice "I won't leave you kid, You can stay here as long as you want and i'll protect you no matter what... I won't let anyone take you..." The minutes passed and Frisk started to calm down slightly. "It's ok baby bones, You can cry, i won't tell anyone." Frisk smiled "Thank you." Sans rubbed circles on her back keeping her calm. It seemed Frisk was always fond of Sans whenever something was upsetting her, he was always someone she could go to. and his fire inside his magic was always the right warmth to calm her down. Nothing like a house fire you'd use normally. Just right for these situations, she felt his soul magic humming with love and telling her he was there. "Sans... I hate to ask but, can i sleep with you tonight, i'm scared to go back to my room and be alone." Sans chuckled "Course you can Kiddo. Whenever something like this happens just let me know, you can come in anytime if you feel scared or hurt." Frisk smiled and there was a long pause as Sans eventually lifted her up slightly and he lied down carefully placing her next to him. "Hey, i normally don't do this unless Papyrus has a really bad night. But since it's you i'll let you listen to a sort of lullaby I know. Hope you don't mind me changing the lyrics, heheh." Frisk smiled her head resting on his jacket "Not at all."

"Now let's see if i can remember how it went."

(The song that would go with these lyrics would go with once upon a time with the ending chords of last goodbye at the end. Hope you enjoy, i had to make this from scratch so this will be interesting.)

(verse 1)  
\- Restless child, fallen down  
-Close your eyes till morning now  
-There is no, need to fight  
-You can stay with me tonight  
-No more dark, no more fear  
-Don't you fret i will be here  
-Hopes and Dream, Care and Faith  
-I will always keep you safe

(verse 2)  
-And when it's morning we can go and play  
-I'll keep an eye on you so you don't stray  
-Always remember which is wrong and right  
-The good day passes into a good night

(verse 1 repeat)  
-When you feel, trapped with fear  
-I'll be there to dry your tears  
-When the dark, pierces through  
-I will be the light for you  
-Promise me, my best friend  
-I'll be by you till the end  
-Rest in peace, knowing love  
-Restless child from up above

Sans finished his song and saw Frisk was pretty much asleep, he place an arm round her to keep her near and he was almost about to try and get some sleep until he heard a quiet voice coming from Frisk "...Sans?" Sans looked down "Hm?" "I love you, I love you all so much." Sans smiled "Love you too... night kid." Frisk smiled too "Goodnight"

Papyrus went to check on them in the morning, they were both fast asleep and Frisk was using Sans as a pillow. Papyrus didn't wake them up..,

**Notes for the Chapter:**

> Last Promise  
> Based on the Indie Video game Undertale By Toby Fox  
> Writtem by Shadowarchives  
> Original Characters by Toby Fox, Temmie Chang, and many other artists  
> Part of the untold episodes  
> Special thanks to Toby Fox, Temmie Chang, the many other people who helped make the game what it was and still is today.
> 
> And you the readers :D
> 
> Without all of you this would not be possible.
> 
> STAY DETERMINED
> 
> Good night :D


End file.
